Power-driven tool



April 18, 1944. s. QBOBINSON ,3 5

' POWER DRIVEN TOOL Filed May 11', 1942 2 Sheets-Sheet 1 f INVENTOR.

A T TO R NEH April 1944- 6. c; ROBINSON 2,347,125

POWER DRIVEN TOOL Filed May 11, 1942 2 Sheets-Sheet 2 8 I I1\IVENTOR.:

AT TOR NEY.

Patented Apr. 18, 1944 POWER-DRIVEN TOOL Girard C. Robinson, Maywood, 111., assignor to Girard Manufacturing Products, Inc., Maywood, 111., a corporation of Illinois Application May 11, 1942, Serial No. 442,492 9 Claims. (c1. 192 -305) This invention relates to improvements in power driven tools.

In the use of power driven rotary tools for tightening nuts, bolts, or the like, or for operating drills, it is necessary to provide mechanism for preventing damage to the tool, motor, or operatin there is an improved spring arrangement for rotatably drawing a J aw member to a new position of engagement after resistance is encountered,

ing parts when the nut or bolt is fully set or when resistance to turning is encountered. It is also desirable in the case oitighteneing a nut or bolt or the like that, when the nut or bolt is almost tight, extra power be provided to give the nut or bolt one or more final turning impacts.

Heretofore various mechanisms have been proposed for accomplishing the above purpose, including cooperating clutch members and springs wherein a relative longitudinal movement takes place between the clutch members when resistance is encountered due to ioreshortening action produced by a wound up spring to cause the clutch to alternately disengage and engage. These devices are complicated and expensive, and because of the heavy springs which it is necessary to use and the arrangement of the clutch members, they are capable of being properly operated only by an air motor of relatively large horsepower, because at each impact, after a resistance is encountered, the motor stalls temporarily making it impractical to employ an electric motor because of the damage wpich results from the stalling.

In my prior patent, No. 2,256,496, issued September 23, 1941, there is disclosed a tool operating unit or adaptor for the above purpose which can be properly driven by a fractional horsepower electric motor without damage to said motor, whereby garages or other institutions having electric drills can readily use the adaptor to convert their drills into tighteners for nuts, bolts,

and the like.

The construction of this prior patent includes the ,use of a single coil spring, surrounding the drive spindle, in which energy is stored by winding up the spring when resistance is encountered. This energy is utilized to cause re-engagement with the driven member and to deliver a driving blow at the time of said re-engagement. This arrangement precludes use of the device for driving in a reverse direction unless the adaptor is first taken apart and the coil spring reversed in position. In addition, with this prior construction, the degree of tightness desired, in tightening a nut for example, can be varied only by changing the size of the single coil spring.

' It is a general object of the present invention to provide a power driven tool construction wheresaid arrangement including one or more expansion springs which normally extend substantially longitudinally of the drive spindle but which are supported outwardly therefrom, the springs being subjected to an elongating force when resistance to rotation of the tool is encountered. This elongating force is produced by a partial rotation of the support for one end of the spring while the other end of the spring is temporarily held against movement, thus causing the spring rangement as above described which cooperates particularly well in conjunction with a tool having a radial jaw and having eccentricmeans for drawing said jaw radially inwardly to disengaged position when resistance to turning movement is encountered.

A more specific object of the invention is to provide a construction as above described which preferably includes the use of a series of helical springs normally extending longitudinall of the unit and arranged in a circle around the driving spindle.

A still further object of the invention is to provide a unit wherein the rotatable jaw carrying member has a fly wheel connected thereto, preferably surrounding a projecting hub portion, to add weight toand increase the magnitude of the blows diivered, said fly wheel also preferably cooperating in the support of one end of each or the helical spring when springs of this type are employed.

A further object of the invention is to provide a construction for power driven tools which can be employed either as an adaptor or be built in as a permanent part of an electric or pneumatic too A further object of the invention is to provide a unit which possesses substantial advantages over the conventional electric nut runners in that it requires less horsepower to drive, consumes less current, is lighter in weight, operates faster, is

less subject to wear and is simple and relatively inexpensive to manufacture. I

With the above and other objects in view, the invention consists of the improved power-driven tool and all its parts and combinations as set forth in the claims, and all equivalents thereof.

In the accompanying drawings, illustrating one complete embodiment of the preferred form of the invention, in which the same reference.

Fig. 4 is a transverse sectional view taken on line 4-4 of Fig. 1;

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 1, showing the jaw in driving engagementj Fig. 6 is a similar view to Fig. 5 showing the jaw after it has been drawn radially inwardly a short distance due to rotation of the eccentric;

Fig. '7 is a similar view showing the jaw drawn radially inwardly to a completely disengaged position and in the Process of moving to a new position of engagement, the dot-and-dash lines indicating said new position; and

Fig. 8 is a side view of the driving spindle and eccentric construction alone.

Referring more particularly to the drawings, the numeral l0 designates a spindle. having a spring holding diskv ll rigidly connected to one end by a set screw l2 or other suitable means, said end of the spindle having a threaded projection i3 of decreased diameter cooperable with an extension it having a threaded bore i5. This threaded bore facilitates connection of the spindle 10 with the spindle of an electric drill it, as shown in Fig. 3, or with any other suitable source of power.

The opposite end of the spindle is in th form of a pilot I! rotatable within a bore it of a'neck portion l9, there being a rotatable part 20 of en- 'larged diameter integral with said neck portion l9 and through which the bore I 8 of the neck extends. The rotatable part 20 isprovided with opposed stops 2| and 22, the ends of which provide shoulders 23 and 24, and 25 and 26 respectively. a

The pilot portion I! and the neck'portion 19 may be formed with cooperating grooves for the reception of ball bearings 21.

On an intermediate portion of the spindle Ill is an eccentric 28, one face 29 of which is adjacent the inner face of the rotatable part20. The eccentric 28 is rotatable within a circular Helical springs each have one end extending into the circular groove 39 of the spring holding member H and held in position by a transverse pin 42. These pins in turn are removably held in position by a spring band 43 which snaps into a groove 44 and which may be readily expanded for removal. The other end of each of the sprin s 4| extends into the groove38 of the fiy wheel 31 and, is held in plac by a removable pin t5 which is removably held in position by a spring band 46 which snaps into a groove 41. As shown in Fig. 1, these springs when in normal position have their longitudinal axes extending longitudinally of the device but spaced radially outwardly from the longitudinal axis of the spindle l0. While it is preferred to employ a circle of springs extending around the driving spindle, any selected number of springs may be employed and for certain types of work only one spring will 'suilice.

Any tool such as the socket wrench head to may be removably connected to the unit by any suitable means, such as the set screw 29 shown inFig. 1.

It is preferred to also utilize an outer shell formed of two sections 49 and 50, which may be screwed together on the threading iii. This shell serves to protect the operating parts and also forms a gripping portion for the hand.

In use of the device when the spindle i8 is driven in the direction of the arrows in Figs. 5,6, and 7, due to the engagement between the jaw end 33 and the shoulder 23 (see Fig. 5), the rotatable part 20 and tool 48 will be rotated. During normal driving conditions the spring connections between the spindle ill and the driving member 3| will cause driving of said latter member. When resistance to turning is encountered, however, as when a nut is almost or fully set, then the eccentric 28 will start to rotate within the opening 30 of the rotatable driving member 3!. This will cause movement ofthe wide portion A of the eccentric from the position of Fig.

5 to the position of Fig. 6 and will cause the jaw.

32' to be drawn radiallyinward-ly along the shoulder 23, as illustrated in Fig. 6. While this is occurring the helical springs 4| will be stretched and laterally'deflected from the position of Fig. 1 to the position of Fig. 2, thus storing up energy. As the eccentric continues to rotate to the position of Fig. 7, the Jay! 32 will ultimately be entirely disengaged from the shoulder-23. The energy stored in the stretched and deflected helical springs 4! will then throw the jaw '32 from the full-line position of Fig. 7 to the dot-and-dash line position therein into engagement with the shoulder 25 of the stop member 22. During such movement the weight of the jaw, augmented by the weight of the fly wheel 31, will deliver a driving impact to the shoulder 28, giving the nut which is being tightened an additional turning opening 30 of a driving member 3|. The driving member has a radially projecting jaw 32 formed the driving member 3| may be formed with cooperating grooves to receive ball bearings 35. The rotatable driving member 3! has a longitudinally extending hub portion 36, and the eccentric 28 extends through said hub portion. Rigidly connected to and surrounding the hub portion is a fly wheel 31 having a circular groove 38 therein. A similar groove 39 is formed in an annular portion 49 of the spring holding disk. I I.

. with eng ing ends 33 and 34. The eccentric and the jaw 32 is the active end and this end coacts inoperation with theshoulder 26 ,of the; stop '22 and with the shoulder 24 of the stop 2112'; Due to the novel arrangement of the,coil springsjthese springs will operate eiiectively to store energy in either direction of rotation.

Due to the use of the radially removable springs arranged as above described, the number. and strength of the springs employed can readily be adapted to best suit the particular piece of work.

For some pieces of work heavier springs than those illustrated may be substituted. Also, certain types of work may require the use of one spring only and all of the other springs can be removed.

By the use of the radial jaw 32, when resistance is encountered and as the jaw is' being drawn from the position of Fig. to the position of Fig. 7, the distance from the center to the driven point is being lessened. Thus less strain is placed upon the driving motor than with devices embodying longitudinally movable clutch members wherein as the clutch members are being operated after resistance is encountered the strain on the motor steadily increases. In addition, with the present invention it is unnecessary to have an eccentric with a long throw and, therefore, there is a minimum of binding torque and strain on the motor when the eccentric is rotating within the opening 30. By having the projecting hub portion 36 with the relatively heavy fly wheel 31 connected thereto, the magnitude of the blow delivered by the jaw 32 is considerably increased. Furthermore, the fiy wheel provides a simple means for holding one of the ends of each of the helical springs.

Various changes and modifications, in addition to those above mentioned, may be made with-' out departing from the spirit or the invention,

and all of such changes are contemplated as may come within the scope of the claims.

What I claim is:

tending in a generally axial direction and spaced radially outwardly from the longitudinal axis of the device connecting the driving spindle with ally deflected when resistance is encountered and to cause automatic re-engagement of said mem- 1. In a power driven tool construction, a tool holder having a rotatable part formed with stop means spaced radially outwardly from the axis 0! rotation, a rotatable driving member having a circular opening therein and normally having a driving engagement with said stop means releasable by radial movement of said member out of engagement with said stop means, means including a driving spindle having an eccentric rotatable within said circular opening of said driving member for effecting said radial movement when said tool holder encounters a predetermined resistance to movement, and means including at least one helical spring connecting the driving spindle with said driving member, said spring being positioned to be longitudinally stretched and laterally deflected when resistance is encountered and to cause automatic re-engagement of able-by radial movement of said member out of engagement with said stop means, means including a driving spindle having aneccentric rotatable within said circular. opening of said driving member for efl'ecting said radial movement when said tool holder encounters a predetermined reslstance to movement, and means including a plurality of helical springs normally exher with said stop means after release, and said springs being resistant to lateral deflection during normal operation and forming the sole driving connection between the spindle and driving memher.

3. In a power driven tool construction, a tool holder having a rotatable part formed with stop means spaced radially outwardly from the axis of rotation, a driving member having a circular interior opening and having a jaw spaced radially outwardly from said opening and normally engageable with said stop means to rotatably drive the tool holder, a driving spindle having an eccentric thereon positioned in the opening of the driving member, said driving member having spring connecting means rotatable therewith and formed with a circular groove, a spring holding disk rigid with said spindle and surrounding the same and spaced longitudinally from the driving member, said disk having a circular groove in its driving member when resistance is encountered to draw said jaw radially inwardly out of engagement with said stop means, with the spring being stretched and laterally deflected during said action, said spring then acting to cause forcible re-engagement of said jaw with said stop means.

4. In a power driven tool construction, a tool holder having a rotatable part formed with stop means spaced radially outwardly from the axis of rotation, a drivingmember having a circular interior opening and having a jaw spaced radially outwardly from said opening and normally engageable with one of said stops to rotatably drive the tool holder, said driving member'also having a longitudinally extending hub, a driving spindle having an eccentric thereon positioned in the opening of the driving member, a fly wheel secured to and surrounding said hub and of greater external diameter than the driving member, a yielding connection between said spindle and driving member normally causing the driving member to rotate with the spindle to drive the tool holder, said eccentric being rotatable in the opening of the driving member-against the tension of said yielding connection when resistance is encountered to draw said jaw radially inwardly out of engagement with said stop, and said yielding means then acting to throw the Jaw rotatably around the eccentric into engagement 7 with the other stop with the weight of the law supplemented by the weight of the flywheel delivering a driving impact. I

5. In a power driven tool construction, a tool holder having a rotatable part iormed with stop means spaced radially outwardly from the axis of rotation, a driving member having a circular interior opening and having a jaw spaced radially outwardly from said opening and normally engageable with one of said stops to rotatably drive the tool holder, said driving member also having a longitudinally extending hub, a driving'spindle one end in connection with said spindle and having its other end connected to said fly wheel to normally cause the driving member to rotate with the spindle to drive the tool holder, said eccentricbeing rotatable in the opening of the driving r member when resistance isencountered to draw said Jaw radially inwardly out of engagement with, said stop means, with said springs stretched and laterally deflected during said action, said springs then acting to cause forcible re-engagement of said jaw with said stop means.

6. In a power driven tool construction, a tool holder having a rotatable part formed with stop means, a rotatable driving member normally having a lug forming a positive driving engagement with said stop means, means for causing release of said engagement when resistance to turning movement is encountered, a driving spindle cooperable with said driving member, and at least one helical spring normally extending lon gitudinally of the device and having its longitudinal axis spaced outwardly from the axis of the spindle, means for connecting one end of said spring to said spindle, and means for connecting the other end of said spring to the rotatable member, said Spring forming the sole driving connection between the spindle and driving member and being positioned to be stretched and latasmiae' holder having a rotatable part formed with stop means spaced radially outwardly from the axis of rotation, a driving member having a circular interior opening and having a jaw spaced radially outwardly from said opening andnormally engageable with said stop means to rotatably drive the tool holder, a driving spindle having an eccentric thereon positioned in the opening of the grooves and engaging the ends of the springs to normally cause the driving member to rotate with the spindle to drive the tool holder, means for removably locking said pins in position, said eccentricbeing rotatable in the opening of the driving member when resistance is encountered to draw said jaw radially inwardly out of engagement with said stop means, with the springs being stretched and laterally deflected during said action, said springs then acting to cause forcible re-engage-,

ment of said jaw with said stop means.

9. In a power driven tool construction, a tool holder having a rotatable part formed with stop means spaced radially outwardly from the axis of rotation, a driving member having a circular interior opening and having a jaw spaced radially outwardly from said opening and normally enerally deflected to store energy when resistance to turning movement is encountered.

'7. In a power driven tool construction, a tool holder having a rotatable part formed with stop means, a rotatable driving member normally having a lug forming a positive driving engagement with said stop means, means for causing release of said engagement when resistance to turning movement is encountered, a driving spindle cooperable with said driving member, and a plurality of helical springs normally extending longitudinally of the device and arranged in a circle around the spindle, means for connecting one end of each of said springs to said spindle, and means for connecting the other end of each of said springs to the rotatable member, said springs forming the sole driving connection be tween the spindle and driving member and being positioned to ,be stretched and laterally deflected to store energy when resistance to turnins movement is encountered.

8. In a power driven tool construction, a tool gageable with one of said stops to rotatably drive the tool holder, said driving member also having a longitudinally extending hub, a driving spindle having an eccentric thereon positioned in the opening of the driving member, a flywheel surrounding said hub and rotatable therewith, at least one helical spring normally extending longitudinally of said drive spindle and having its longitudinal axis spaced radially outwardly from the longitudinal axis of the spindle, said spring having one end in connection 'with said spindle and having its other and connected to said fiywheel to normally causethe driving member to rotate with the spindle to drive the tool holder, said eccentric being rotatable in the opening of the driving member when resistance is encountered to draw said jaw radially inwardly out of engagement with said stop means, with said springs stretched and laterally deflected during 

